Method of making a bolt anchor shield



Sept. 11, 1956 J. E. JACKSON 2,762,119

METHOD OF MAKING A BOLT ANCHOR SHIELD Filed April 22, 1953 lob IN V EN TOR.

JOHN E. JACKSON BY Unite tates ice METHOD OF MAKlNG A BOLT ANCHOR SHIELD John E. Jackson, Warrensville Heights, Ohio Application April 22, 1953, Serial No. 350,431

2 Claims. (Cl. 29-533) This invention relates to improvements in bolt anchors and including improvements in an expansible shield and a method of making the same.

One of the objects of the present invention is to provide a simple expansion shield for coaction with an anchor bolt, said shield adapted to be made in an inexpensive manner and yet to operate so as to anchor the bolt tightly when in use.

Another object of the present invention is to provide a novel method of making an expansion shield for use with an anchor bolt, wherein a hollow generally cylindrical sleeve is provided having a base pOrtion at one end thereof and having a plurality of arcuate fingers extending axially from the base portion and concentric with it, together with a series of parallel generally annular corrugations extending around all of the fingers at right angles to the axis of the sleeve and providing means whereby the shield will grip the sides of a hole so as to anchor a bolt.

Another object of the present invention is to provide an expansible shield of the type described in the preceding paragraph adapted to coact with a frusto-conical plug or nut adapted to be threaded on an anchor bolt and to expand the fingers of said shield, wherein said corrugations increase in depth from the free ends of the fingers toward the base portion so as to progressively increase the spread of the fingers as the bolt is tightened into the plug or nut.

A further object of the present invention is to provide an expansible shield of the type described in combination with a dual expansion frusto-conical sleeve adapted to be carried by the nut or plug down between the fingers of the expansible shield so as to expand said fingers to grip the sides of an anchoring opening too great in diameter to be efiiciently gripped by the fingers of the expansible shield alone.

A further object of my invention is the provision of a novel method or" making an expansible shield of the type described comprising blanking out a flat sheet of low carbon steel to provide a continuous strip along one side of the sheet and the plurality of separate parallel finger portions extending at right angles to this strip, after which one face of the blank is rolled or stamped to provide a plurality of corrugations extending across the finger portions and parallel to the longer dimension of the strip, and thereafter forming the sheet generally into a cylinder with the strip providing a ring base portion with arcuate fingers extending axially from the base portion and concentric with it. In this method, the low carbon steel is work hardened by the rolling or stamping operation so as to make a more efiicient expansible shield with the spring characteristic of the work hardened steel and a greater ability of the fingers to expand outwardly because of the corrugations extending crosswise of the fingers.

Other objects and advantages of my invention will be apparent from the accompanying drawings and description and the essential features thereof will be set forth in the appended claims. In the drawings,

Fig. 1A is a top plan view of the shield of Fig. 1.

Fig. 1 is a side elevational view of an expansible shield made according to my invention.

Fig. 2 is a top plan view of a blank for forming the device of Fig. 1 after the same has had corrugations rolled or stamped into it.

Fig. 3 is a transverse sectional view through the device of Fig. 1 showing the fingers thereof expanded to grip a hole and showing a plug or nut in the finger expanding position which it would occupy when threaded upon an anchor bolt.

Fig. 4 is a central sectional view showing a modification of the expansible shield and showing a dual expansion frusto-conical sleeve with a nut or plug inside the same in the position they would occupy when inserted into a hole prior to expansion of the shield.

Fig. 5 is a view similar to Fig. 4 showing the position of the part when the nut has been screwed down upon an anchor bolt and the frusto-conical sleeve has been drawn toward the base of the expansible shield, thus expanding the fingers to grip a hole for anchoring purposes.

Fig. 6 is a central sectional view through the dual expansion frusto-conical sleeve of Figs. 4 and 5 while Fig. 7 is a transverse sectional view taken along the line 7-7 of Fig. 5.

This invention relates to an expansible shield as shown in Figs. 1 and 3 for use with an anchor bolt wherein my expansible shield and a frusto-conical plug or nut are first assembled on an anchor bolt, the entire assembly is pushed into a previously formed hole, after which the bolt is tightened and thus threads into the nut, causing the nut to pass down between the fingers of the expansible shield which spreads out the fingers and causing the fingers to grip the sides of the hole. Such fastenings are commonly found holding wooden or metal plates or metal channels in place on the roof of a mine although other uses of this type of invention are well-known.

One form of my device is shown in Figs. 1, 2, and 3. A flat sheet of low carbon steel is blanked out approximately into the form shown in Fig. 2. This blank 19 has a continuous strip 19a extending along one side of the sheet and a plurality of separate parallel finger portions extending at right angles to the strip 1%. Suitable rolls are then passed crosswise of the strips 10b to provide a plurality of corrugations ll extending across the finger portions and parallel to the longer dimension of the strip 10a. These corrugations 11 may also be provided by a punch press operation of stamping and forming between V specially designed dies. In one form of my invention intended to provide an expansible shield approximately 1% inches outside diameter, the dimension A of Fig. 2 is inch and the dimension B is 2 /2 inches and there are ten of the corrugations 11, all of the same width and same radial depth and therefore these corrugations are about inch apart. However the dimension may vary. The rolling or stamping of the corrugations 11 in a strip of low carbon steel, such as SAE 1020 will work harden the steel somewhat so as to give it better characteristics for resisting abrasion and giving the fingers a little more spring-like quality and stiffness than is found in low carbon steel as received from the mill. The rolling or stamping operation causes the ends of strip 10a to curve upwardly providing a concavity, and further forming operations are used to further curl the sheet with the concave face inside until a complete generally cylindrical form is provided as shown in Fig. i.

It will be noted that the expansible shield 12 shown in Figs. 1 and 3 is a generally hollow cylindrical sleeve having a base ring portion at its lower end and a plurality of arcuate fingers extending axially from the base portion and concentric with it. The series of parallel generally annular corrugations 11 extend entirely Patented Sept. 11, 1956.

i the sleeve.

r a, around all of the fingers at right angles to the axis of In this form of my device,-four fingers are provided although it will he understood that my invention is not limited to. that specific number of fingers.

Three. fingers Could. ery ll. be used. nd o he mber would be acceptable. These fingers are, separatedfby slots 13. which are adapted to cooperate with, a nut; or plug 14 having diametrically oppositely extending Wings 15 which are adapted to enter two. of the slots 15, so.

as to prevent the not from tu ning when it is threaded on the anchor bolt. It will be noted in Fig. 1 that the base portion 10:: is formed into a, generally continuous ring save for an axially extending slit 16, through. the base portion which is preferably provided so as to give a p i g pable. o expansion- In. some. cases; it y de irab o wel he as P rti n 10a in a solid ng, but I pref r the sp t r ns- Wh n the an n ble shie d of Fig} oge h the nut, is placed in an opening drilled into the earth above a mine roof or otherwise, the nut 14 is threaded onto an anchor bolt (not shown) so that the unexpanded shield with the nut and bolt are entered into the opening prior to tightening the bolt. In this case, the outside iameter of the shield 12 is approximately 1% inches and can be freely entered into a hole of slightly larger size. Thereafter, the bolt is turned to draw. the nut 14 down on the threads of the bolt and this causes the nut to travel toward the base portion Illa, thus expanding the fingers 10b to. the position shown in Fig. 3. The corrugations 11 all parallel to the base ring portion make the fingers lfib more flexible for bending outwardly to the position shown in Fig. 3. The purpose of the split ring base portion 10a will now be apparent as it provides structure which permits the base ring portion to expand as shown in Fig. 3 so as to permit more free expansion of the shield to anchor itself in the hole. The wings 15 travel down the slots 1 3 as the nut is drawn down to the position of Fig. 3 and this prevents relative rotation between the nut Hi and the expansible shield 12. The sharp edges 1 1a at the ends of corr u. gations 11 and adjacent slots. 13 bite into the wall of the hole to stop rotation of the. shield in the hole.

In the form of my device shown in Figs. 1 and 3, it will be noted that the inner and outer crests of the corrugations l1 lie substantially on imaginary cylinders cQncentric with the base portion 10a.

In the modifications shown in Figs. 4 and 5, there. re two fundamental differences as compared to the first described form. corrugations 119 are again parallel to the base portion 10' and extend generally annularly about all four fingers. and all of' the corrugations are parallel to each other. However, here the, outer crests. of the colf llgations again lie substantially on an imaginary cylinder concentric with the base portion 10, but the inner crests of the corrugations lie substantially on an imaginary frusturn of a cone coaxial with and diverging away from the base portion 10. In one form of my invention where the expansible shield of Fig. 4 has a total length of 3 /2 inches, the base ring 10" is about inch high and the corrugations occupy 2% inches, there being about 8 such corrugations. However, the number of corrugations may be varied more or less. shield has a n rm l outside diamet r f. 1% inche nd the inside im nsi n C is -9 0 nch h le he inside dimen i n 1; is .765 inch. In other words, the internal diameter of he n n-e p h eld. s sh wn in F at apers. 0. .6.5, in h in i m r f m the top o th ottom.v It resul s from this construction, that if the nut 14 of Fig. 3 is. drawn down in the shield of Fig. 4, the fr e ends, of the finger will be extend d o a gre t r diam t rhan that n. n g. 3 e au e of the re t r, dep h at the orr ga n 1 a compar h. he corr g tion k1 4i...

In the shield shown in Fig. 4, the top corrugation atlltlu, is appro m te y .2 n h in v rt cal idth, at ep h In Fig. 4, it will be noted that the whereas the bottom corrugation at 11% is approximately .359 inch in depth.

It will be understood from} the above that the shield of Fig. 4 may be utilized with the nut 14 without further change in my invention. However, another modification is illustrated in Figs. 4 and 5. Here a dual expansion frusto-conical sleeve 17 is provided, having an inside surface tapering towar-d the base portion of the pansihle hield and ap o en er bet en; the outer ends of the fingers 10" when in their unexpanded position as shown in Fig. 4. Prefer-ably, the inside face of the sleeve 17 is; provided with an annular shoulder 18 near the bottom so as to hold the nut 14 when it reaches the bottom of this sleeve. Preferably, but not necessarily, the slope on the inside surface of the sleeve 1''? will correspond to the slope on the outside face of the nut 14.

Some means is provided to prevent relative rotation of the nut 14. withthe bolt 19 as. the parts are pulled down from the position of Fig. 4 to that shown in Fig. 5. The wings 15 of the nut 14 may be of suflicient radial extent and. the sleeve 17 may be provided with slots. 17a extending along its side walls from the upper base of larger diameter down to the shoulder 18;, so that the wings 15 will pass outwardly through the slots 17:; and into th eslots 13a between the fingers 10" as the bolt is. threaded; into the nut 14. Another manner of doing this, is to provide sufiicient friction between the nut 14 and the interior surface of the sleeve 17 to prevent sub. stantial turning and then provide wings 20 indicated in dot-dash lines in Fig. 6 extending radially outwardly and diametrically opposite each other on the sleeve 17. These wings, entering between the fingers 10" would prevent rotation of the sleeve 17 relative to the shield 12.

With. the parts in the position indicated in Fig. 4., the assembly of parts there shown may be started on a bolt 19 (not shown in Fig. 4) and the bolt may be pushed upwardly into the hole in the earth above a mine roof. This assembly would be entered into a hole of approximately 1% inches diameter. After the parts are in po.-. sition the bolt 19 may be turned so as to thread; the nut.

14 downwardly into the expansible shield 12 as. shown" in Fig. 5 causing the free ends of the fingers 10" to be expanded outwardly into frictional engagement with the sides of the anchoring hole. The base ring portion 10- being split, may expand as shown in Figs. 5 an 7 to give further freedom of expansion to the entire an chorage.

With an expansible shield 12- having the dimensions previously indicated herein, utilizing the nut 14 alone, ithout he sleeve 1 he fi g r :0 w ll g p f rm y in an opening having about 1% inches diameter. Uti: lizing the sleeve 17 also, together with the nut 14, as shown in Figs. 4 and 5, the free-ends of the fingers. 1 0 may be expanded to grip firmly in a hole having approximately 2 inches diameter.

What I claim is:

1. The method of making an expansible shield for a bolt anchor comprising blanking out a fiat sheet of low carbon steel to provide a continuous strip along one side of the sheet and a plurality of separate parallel finger portions extending at right angles to one edge of said strip and having narrow spaces between them and Pr v in sh p edge ng he pa llel side of id ng r. por ions t e a e o s d lank, farm ng b h. faces. of said fingers to provide a plurality of corruga= ons ex en ing c o d nger Po i s p r lle he. longer d m n of. sa ip y pp ying rmin Pressur o the steel. blank, o th t i fw rk hardened and becomes more springlike, and thereafter forming said sheet into a general cylinder with said one face of said b a k on. h out e an i h a d s ip pro idi g a r ng ba p r i n. wi h each, Q s i finge are ate. and xt n ing ax all r m ai as po on and eeneehtr e therewith.

References Cited in the file of this patent UNITED STATES PATENTS OLeary Sept. 18, 1906 Masor June 23, 1914 Joseph Jan. 4, 1916 Van Antwerp Aug. 8, 1916 Kraft Jan. 31, 1922 Wahlberg Oct. 28, 1924 Pleister et a1. June 26, 1928 Keller Jan. 4, 1938 McIntosh Apr. 15, 1941 Marks Mar. 11, 1952 

